The influence of convective heat transfer on flow stability in rotating disk chemical vapor deposition reactors Page: 4 of 40
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Printed June 1997
The Influence of Convective Heat
Transfer on Flow Stability in Rotating Disk
Chemical Vapor Deposition Reactors
W. S. Winters and G. H. Evans
Thermal and Plasma Processes Department
Sandia National Laboratories / California
Mechanical Engineering Department
University of California, Berkeley
The flow and heat transfer of NH3 and He have been studied in a rotating disk system
with applications to chemical vapor deposition reactors. The flow field and disk heat flux
were obtained over a range of operating conditions. Comparisons of the disk convective heat
transfer were made with the infinite rotating disk results to appraise uniformity of transport
to the disk. Important operating variables in a rotating disk reactor include disk spin
rate, disk and enclosure temperatures, flow rate, composition, pressure, and temperature
of the gas mixture at the reactor inlet. These variables were studied over ranges of the
primary dimensionless variables: the spin Reynolds number, Re,, the disk mixed convection
parameter, MCPd and a new parameter, the wall mixed convection parameter, MCPW. Inlet
velocities were set to the corresponding infinite rotating disk asymptotic velocity. Results
were obtained primarily for NH3. These results show that increasing Re, from 314.5 to
3145 increases the uniformity of the rotating disk heat flux and results in thinner thermal
boundary layers at the disk surface. At Re, = 314.5, increasing MCPd to 15 leads to
significant departure from the infinite disk result with nonuniform disk heat fluxes and
recirculating flow patterns; the flow becomes increasingly complex at larger values of MCPd.
At the larger value of Re, of 3145, the results are closer to the infinite disk for MCPd up
to 15. For large negative (hot walls) and positive (cold walls) values of MCPW, the flow
recirculates and there is significant deviation from the infinite disk result; nonuniformities
occur at both values of Res. The influence of MCP, on flow stability is increased at larger
MCPd and lower Re,. In order to determine the influence of variable transport properties
(i.e. viscosity and thermal conductivity variation with temperature), calculations were made
with He as well as NH3; He transport property variation is low relative to NH3. The results
show that the flow of NH3 is less stable than that of He as MCPd is increased for MCP, = 0
and Re, = 314.5.
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Winters, W.S.; Evans, G.H. & Grief, R. The influence of convective heat transfer on flow stability in rotating disk chemical vapor deposition reactors, report, June 1, 1997; United States. (digital.library.unt.edu/ark:/67531/metadc690396/m1/4/: accessed October 19, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.